JPS58154221A - Method of producing niobium electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a modified method for manufacturing a friendly electrolytic capacitor using a niobium element.

Conventionally, a dielectric layer has been formed by anodizing a niobium element in an electrolyte solution containing chloride as an electrolyte.

[Conventional technology and electric point]

In traditional manufacturing methods, the dielectric layers of niobium electrolytic capacitors are borates, phosphates, and sulfates.

It is formed by anodizing a niobium element in an electrolyte solution containing citrate or the like. The niobium element thus obtained and coated with an anodic oxide film is housed in a condenser container filled with an appropriate electrolyte solution together with an appropriate counter electrode (cathode) (via a spacer if necessary). A DC voltage equal to or lower than the anodizing voltage during anodization is applied between the niobium anode and the cathode to perform an aging treatment, and then the capacitor is made into a round capacitor.

Nine-op electrolytic capacitors manufactured using conventional manufacturing methods have a large leakage current throughout the operable voltage range, and the addition of leakage current to the applied voltage is significant, so it is difficult to compare the rated voltage with the surge voltage. There was a drawback that it had to be made significantly lower.

[Purpose of the invention]

The present invention aims to improve the drawbacks of the 9 niobium electrolytic capacitor produced by the above-mentioned conventional manufacturing method.
Characteristic 11 is that the niobium element is positively oxidized in a chloride electrolyte water solution to form a Vcll electric layer on the surface of the niobium element, and then annealed in an oxidizing atmosphere to form an electrolytic capacitor. [Summary of the Invention] The capacitor wire manufactured by the manufacturing method of the present invention has a region in which the change in leakage current with respect to a change in applied voltage is small compared to a capacitor constructed by a conventional manufacturing method, that is, the leakage current is proportional to the applied voltage. The characteristic is that the region where the leakage current increases rapidly according to Ohm's law is extremely wide, and the region where the leakage current that appears after this region increases rapidly as the applied voltage increases, that is, the region where the leakage current follows the Poole-Frenkel law is very narrow. ing. □・ Therefore I! Rated voltage of the capacitor 1 than in the case of east
(for equal surge voltages) can be set significantly higher.

To concretely demonstrate the effects of the invention using an example, as shown in Figure 1, in a conventionally manufactured capacitor (reference example), the region where the leakage current follows Ohm's law is approximately the formation voltage (surge voltage). This is a very narrow range up to a voltage of 115.

On the other hand, the leakage current of the capacitor (embodiment) manufactured by the manufacturing method of the present invention occupies a very wide range from about v5 to voltages above v5 of the surge voltage, which flows according to Ohm's law.

Furthermore, the slope of the leakage current with respect to the applied voltage in the Ohm's law region is also very small compared to the case of conventionally manufactured capacitors, as shown in the figure.
It is four times smaller, indicating that the increase in leakage current as the applied voltage increases is extremely small.

It can be used in any shape such as a niobium element box, HA shape, sintered body shape, sputtered film shape, or vapor deposited film shape.

Anodization of niobium elements can be carried out using hydrogen chloride, alkali metal chlorides, alkaline earth metal chlorides, ammonium and primary, secondary, tertiary, and quaternary organoammonium chlorides, iron group metal chlorides, etc. , a zinc group metal chloride, an aluminum metal chloride and a transition metal chloride such as chromium, mag/ga/, etc., and a chloro complex salt of a transition metal in an aqueous solution.

The modification of these chloride electrolytes is selected taking into consideration the temperature, formation current vli degree, degree formation voltage, but the effective range is chloride ion concentration of 2 to 25? -1 ov'-8.

Furthermore, 2?・If it is less than i ovJ, no improvement in leakage current R characteristics can be expected, and if it is more than 925f bow 0ν1, conde/l
The capacitance characteristics become very poor.

11 degrees is the chlorine ion am of the solution and the chemical formation current density.

-15 to 10, taking into account the current/chilling voltage etc.
Selected within the range of 0c.

Kaseiden Takishodo has no effect on leakage current characteristics.

Forming voltage has a significant effect on leakage current characteristics, and below the scintillation voltage, forming voltage is high;
IIC% property improves. However, if the voltage exceeds the scintillation voltage, it becomes significantly worse.

Annealing is normally carried out in an oxygen atmosphere, a mixed gas atmosphere of oxygen and nitrogen, or a mixed gas atmosphere of oxygen and a noble gas, but it can also be carried out in an oxidizing gas atmosphere such as nitrogen monoxide, nitrogen dioxide, or chlorine. However, it is difficult to carry out the process in an atmosphere of a transitional gas such as hydrogen or in a vacuum. Annealing in a transient gas atmosphere or in a vacuum will conversely increase the leakage current of the oxide film.

The annealing temperature is preferably in the range of 3ON00C, aoo
Below c, the effect of annealing is hardly noticeable #1, and
oor or higher, reverse lIc occurs due to crystallization of the oxide film, etc.
This is not preferable because it causes an increase in the current.

It is obvious that the annealing time is short when the temperature is high, and long when the temperature is low, but the anneal time of 5ooc is 5 minutes @
degree, 700G O is 10 minutes m degree, 6001:' is 20 minutes Ii degree, goor is about 40 minutes, 40
It takes about 70 minutes for 0t and 120 for 300C12)
It's a moderate amount of change.

The subsequent aging may be done with a strong chloride f# liquid liquid medium, which is dangerous. Does aging mean that halogen ions are not included, or even if they are included, the concentration is 10?・+o
Must be carried out in an electrolyte solution below JtJ. The DC voltage applied during aging is equal to or lower than the formation voltage, and the application time and temperature are the same as before.

To manufacture electrolytic capacitors after the aging process! A
Conventional techniques are applied to all necessary techniques.

The structure of the niobium electrolytic capacitor according to the present invention is as follows for each of the foil type, sputtered film type, vapor deposited film type, sintered body, and type 1.

(1) After forming an oxide film on the entire surface of the membrane-type capacitor niobium foil, it was wrapped with an ion-permeable porous diaphragm in between and wrapped with a suitable gold foil to serve as the cathode, and then impregnated with an appropriate electrolyte solution. Then, fill it with the same electrolyte solution, place it in a suitable container, remove the lead, and seal it.

(-) After sputtering or vapor depositing niobium on both sides of the sputtered film and vapor-deposited film type capacitor substrate, an oxide film is formed on the surface of the niobium film, and then an ion-permeable porous 11M film is sandwiched between them to form a 111i film. After laminating it with gold maple foil and impregnating it with a suitable electrolytic JXX liquid, it is housed in a loud container filled with the same electrolyte solution, and the lead is taken out and sealed.

(iM) Sintered body and linear capacitor An oxide film is formed on the entire surface of the niobium sintered body or the winding, and an appropriate electrolyte solution is impregnated. Place it in a metal can so that the oxide film does not come into contact with the can, take out the anode lead, and seal it.

[Embodiments of the invention]

Next, the present invention will be explained using examples.

Dimensions, width 2. Ocm, fear 25. □z, thickness 205m
After removing the niobium foil with a purity of 99.985 weight, the surface was treated with a 7M ammonium fluoride aqueous solution, and then chemically formed to form a 1 liter oxide film on the niobium surface in the following manner. I let it happen. 4); Example 1: A niobium foil was immersed in 25C 11.0M@@ (CJ soaking strength 11r Ion/view) to form S and the like, and a platinum electrode was immersed as a counter electrode, and then a current was applied between the two electrodes. A direct current of VVfJ [2.5 mA/d was applied to perform anodic oxidation until the potential difference between the two electrodes was suitable for 50 V.

The anodic oxide film was then annealed in the following manner.

Sample M: 9 samples b treated for 5 minutes in 5oor air
: 9 samples treated in air at 700C for 10 minutes c: 5
Sample d treated in air at 00C for 40 minutes: 300C
Example 2 near 0U treated for 120 minutes in the air at 7. A niobium foil was immersed in an aqueous solution of ammonium chloride (4-1 concentration: 7t ion β) to serve as an anode, a platinum electrode was immersed as a counter electrode, and a direct current with a current density of JlLOm was applied between the two electrodes. The anode is saponified in a trench where the potential difference between the two electrodes reaches SOY K9.

Then, perform an annealing treatment on the anodic oxide film as follows.

Sample y: Treated for 5 minutes in 5 ooc air, sample G without near-annealing Example 3: IOG 4. S MtJi conversion≠Drygum aqueous solution (0-concentration 4.5t・tov'J,) A niobium foil was immersed as an anode, a platinum electrode was immersed as a counter electrode, and a current density of 4.0 mA/d was applied between the two electrodes. DC current was applied to perform anodic oxidation until the potential difference between the two electrodes reached 50V.

Then, the anodized film was subjected to a nanyl treatment in the following manner.

Sample H: 9 samples treated in air at 800C for 5 minutes without near-annealing Example 4: Niobium foil immersed in 1.0M calcium chloride aqueous solution at 100C (Q″″ concentration 2.01i o Q/J) After immersing a platinum electrode as a counter electrode, a direct current with a current density of 0.5 mA/a11 was applied between the two electrodes to perform anodization until the potential difference between the two electrodes reached 50 V.

Next, apply annealing treatment to the anodic oxide film using the following procedure.

Sample J: A sample treated in air at 800C for 5 minutes without near-annealing. As a reference sample representative of a conventional niobium electrolytic capacitor, a niobium pentoxide film was formed on the niobium surface in the following manner. That is, a niobium foil was immersed in a 0.5M ammonium borate aqueous solution of reference sample = 25c to serve as an anode,
After immersing a platinum electrode as a counter electrode, a current density of 1.
Anodic oxidation was performed by applying a direct current of 0 μm/− until the potential difference between the two electrodes reached SOV.

The obtained oxide film was then annealed in the following manner.

Reference sample 1: Treated in air at 800C for 5 minutes Reference sample 2 No near annealing treatment Each of the above 1311 samples was separately heated at 25C for 0.5M
The platinum electrode was immersed in an aqueous ammonium pentaborate solution.
A direct current of 50 V was applied between the two electrodes (as a cathode) and maintained for 2.5 hours to perform aging (reformation) treatment.

After that, each sample foil was coated with a width of 2.03 mm. length 2
5LO3, medium 2. Otx, length 2! L
O1, thickness 10 bound* 99.99 weight - tin #i
t-overlap '1: Wrap it into a cylindrical shape to create a capacitor element.

Soak the 13 completed capacitor elements in a 2M ammonium pentaborate/ethylene glycol solution, and impregnate the entire element with the ammonium pentaborate/ethylene glycol solution under reduced pressure. After impregnation, it was placed in a cylindrical plastic container and filled with 2M ammonium pentaborate/ethylene glycol # solution, and the lead was taken out and sealed.

Thus, a total of 13 capacitors were manufactured, including 11 types of capacitors according to examples of the present invention and two types of capacitors, a reference example corresponding to a conventional niobium electrolytic capacitor.

Next, in order to soften the leakage current 1%E% of the 13 types of capacitors, we applied a 50V DC positive bias under 25C and aged them for a day and night, and then applied a specified DC positive bias under the same 25C for 1 hour. was applied, and when the current flowing between both terminals of the capacitor became completely constant, the current value of 1 was taken as the leakage current and plotted against the applied voltage. The results are shown in FIGS. 1 and 2. [Effects of the Invention] As can be seen in the figures, the niobium electrolytic capacitor of the present invention is significantly superior to conventional capacitors in terms of leakage current characteristics.

FIG. 2 is a line diagram showing changes in leakage current of a niobium electrolytic capacitor manufactured by M with respect to applied voltage.

Attorney: Kensuke Norichika (and 1 other person) Figure 1 egg mt five (v)

Claims (1)

[Claims] In a method for manufacturing a niobium electrolytic capacitor, 2-25P
The niobium element was anodized in an aqueous chloride electrolyte solution containing the chloride ions of -ii, and then exposed to air. Annealing treatment in an oxidizing tS atmosphere such as oxygen, and further 1
A DC voltage equal to or lower than the anodizing voltage during anodization is applied between a suitable counter electrode (and cathode) in an electrolyte solution containing no halogen ions of 0'''JFioa/J or more, followed by an aging treatment. A method of manufacturing a niobium electrolytic capacitor whose q# characteristic is to be later finished into an electrolytic capacitor.